The viruses that (since 1996) constitute the taxonomic order Nidovirales (Arteriviruses, Coronaviruses, Toroviruses and Roniviruses) cause significant disease in humans, simians, a large number of livestock species, poultry, shrimp, insects and whales. Human coronaviruses are the second leading cause of the human cold, accounting for acute economic costs, and the recent discovery of a previously unknown coronavirus that is now associated with Severe Acute Respiratory Syndrome (SARS), a newly emerged infectious disease in humans, underpins the importance of scientific research in this field. In addition, in the late 1980's, porcine reproductive and respiratory syndrome virus (PRRSV), the newest member of arteriviruses family emerged in Europe and North America simultaneously and is now endemic worldwide. The emergence of these new viruses have changed the focus of nidovirus research and enticed many new investigators into this field of study. The International Nidovirus Symposium, a triennial meeting, is unique in bringing together scientists engaged in various aspects of nidoviruses study including molecular biology, pathogenesis, immunology, evolution and epidemiology and vaccine development. For newcomers to this field, the symposium is an excellent opportunity to obtain an overview of the most recent developments, and to discuss ideas with experts in particular areas of nidovirology. Several graduate student and th postdoctoral travel awards will be given to encourage young scientists to attend this XII International Nidovirus Symposium. In addition, invited guest speakers will discuss other important research areas so that participants could update their knowledge bank and learn of new advances brought about in the larger universe of viruses. PUBLIC HEALTH RELEVANCE: The XII International Nidovirus Symposium is a high quality scientific meeting that provides a venue for virologists who are working on important group of positive stranded RNA viruses that pose a significant threat to the public health to share their research findings with other scientists from around the world. The primary objective of this symposium parallels the scientific mission of the NIH. This symposium is unique in bringing scientists together who study different aspects of nidoviruses, such as molecular biology, pathogenesis, evolution and epidemiology, immunology and vaccine development. The cost of the symposium will be covered by the registration fees and donations from private industry. However, under current economic conditions obtaining donations from industry will be difficult, and therefore, as th organizers of the XII International Symposium, we are requesting support through this conference grant application. 1